FOX04-DRI 10mg

What FOXO4-DRI (Proxofim) is

FOXO4-DRI, also sold as Proxofim, is a 46-residue synthetic peptide built entirely from D-amino acids, with an average mass of about 5358 g/mol. The letters DRI stand for D-retro-inverso: the parent sequence is written in reverse order and every residue is switched from the L to the D form. The two inversions together leave the side chains in roughly the same spatial arrangement as the parent while the backbone runs in the opposite direction, which makes this one of the few peptide catalog names that genuinely describes the chemistry.

The chain consists of two joined segments. The first is derived from an interaction motif of the FOXO4 transcription factor, and the second is a strongly basic stretch rich in arginine and lysine of the type used as a cell-penetrating carrier sequence. It is among the largest and most structurally unusual peptides in the catalog. The spelling FOX04, with a zero, occasionally seen in listings is a transcription error for the same compound.

FOXO4-DRI 10mg specification

How FOXO4-DRI is analyzed

The basic tail dominates everything. Its run of arginines and lysines interacts strongly with residual silanols on silica columns, so peak shape depends heavily on column choice and on the ion-pairing additive, and broad or tailing peaks are often a method artifact rather than an impurity. Every one of those basic side chains can hold a counter-ion, which is why net peptide content on this compound falls much further below chromatographic purity than on a typical peptide. Electrospray spectra show a long series of highly charged ions that should deconvolute to about 5358. Two identity limits apply. Mass cannot tell a retro-inverso peptide from its parent, because both share one formula, and routine amino-acid analysis after hydrolysis returns the same composition whether the residues are D or L. Only a chiral method can confirm the all-D configuration.

The reverse-phase HPLC result for this construct is shown on the page you are reading. In place of lot or batch codes, the crimp and cap color on the vial links it to that result.

Research contexts for FOXO4-DRI

• Cell-free protein-protein interaction assays of the FOXO4 and p53 binding interface
• Design and comparison studies of retro-inverso peptides against their L-parent sequences
• In-vitro protease digestion experiments contrasting all-D and all-L chains
• Chiral analysis and counter-ion quantification methods for large, highly basic peptides

Proxofim is supplied for in-vitro experimental and analytical use in the laboratory, and is not intended for use in humans or animals.

FOXO4-DRI questions

Is Proxofim the same as FOXO4-DRI?

Yes. Proxofim is a trade name for the identical D-retro-inverso construct, and FOX04-DRI is a misspelling of the same name.

Can mass spectrometry confirm the retro-inverso structure?

No. The retro-inverso peptide and its parent contain the same residues and therefore the same formula and mass. Mass confirms composition; chirality and sequence direction need other methods.

Why is net peptide content so far below HPLC purity for FOXO4-DRI?

The many basic residues each bind a counter-ion, so a large share of the powder mass is counter-ion rather than peptide. Purity and content answer different questions.